Experiments with Supersonic Beams as a Source of Cold Atoms

atoms or molecules are slowed using pulsed magnetic fields. Since most atoms and
some molecules are magnetic dipoles in their ground state or an easily accessible
metastable excited state, this method of producing cold slow samples is very general.
Pulsed magnetic fields are created using high current electromagnetic coils, which the
atoms or molecules travel through. The magnetic moment of the atom or molecule
means that some are repelled by magnetic fields, leading to a loss of energy as the
atom enters the coil and slowing them down. Switching off the coil before the atoms
can exit means they do not regain this energy. Multiple coils in sequence are used to
bring the beam to rest in the lab frame. The coilgun apparatus, including coil design
and characterization, electronics, and beam preparation, is described in this chapter.
The data presented shows control of the velocity of beams of metastable neon and
molecular oxygen.
Chapter 5 discusses the ongoing project to trap atomic hydrogen. Hydrogen
is particularly interesting since it is the simplest atom and has served as a Rosetta
Stone for atomic physics. Since the magnetic moment to mass ratio of hydrogen
is the highest among all atoms, it is ideally suited to the coilgun method. The
hydrogen specific coilgun and trap are described and characterized. Simulations of
the hydrogen trapping process are presented. Prospects for two-photon spectroscopy
of trapped hydrogen are discussed, and the laser to excite the two-photon transition
is described. Future improvements to the coilgun apparatus are presented. Finally,
a proposed adaptation of single photon cooling to atomic hydrogen using RF-dressed
states and the two-photon transition to further cool a magnetically trapped sample
is discussed.
6